GOTHENBURG, Sweden — All jet lag is not created equal, according to new data released today from Sleep Cycle, the world’s first and most popular smart alarm clock app.
The new report from the [sleepcycle.com] Sleep Cycle Institute [sleepcycle.com] looked at more than 1.5 million nights’ worth of sleep data from people who traveled east (forward in time), west (backward in time) and without traversing any time zones (the control group) to get a quantitative look at how travel interferes with our sleep.
The most significant finding of the new report is that traveling east (forward in time) is significantly worse for sleep than traveling west (backward in time). In fact, it seems that westbound travelers may enjoy better sleep than usual.
Time, Travel and Shuteye
Looking at the first five days of travel, not only do people enjoy less severe jet lag when they travel west, but their quantity of sleep, quality of sleep and wake-up mood actually improve. This is true not only compared to eastbound travelers but also to people who travel without moving through any time zones — and the effect is greater the further west they go.
On the other hand, the further east people travel, the poorer their quantity of sleep, quality of sleep and wake-up moods become:
Average Average Average
Time zones crossed sleep quality wake-up mood time in bed
-9 hours 76% 62% 7 hrs 31 mins
-7 hours 75% 64% 7 hrs 26 mins
-2 hours 74% 62% 7 hrs 18 mins
None (control group) 73% 60% 7 hrs 15 mins
+2 hours 73% 60% 7 hrs 9 mins
+7 hours 67% 59% 6 hrs 57 mins
+9 hours 66% 57% 6 hrs 48 mins
What most travelers seem to have in common, regardless of how much or whether or not they’re traveling through time, is that they sleep fairly well the first night of their trip but see a marked decline in sleep quality on night two. On day five or six, sleep quality peaks, and their sleep returns to normal around day 10. This is seen in time changes as low as three hours but is augmented when traveling further distances.
Observations From the Experts
Sleep Cycle asked some of the Sleep Cycle Institute panelists for further commentary about jet lag. Australian sleep expert, neuroscientist and health educator Dr. Chelsie Rohrscheib said jet lag from vacation travel is unlikely to have any lasting negative effects but can be a serious problem for frequent travelers like airline crew members.
“Long-term jet lag is serious because it's essentially the same as being chronically sleep-deprived,” she said. “The bodies of chronically jet-lagged individuals can't function properly because the brain has a difficult time sending the appropriate signals when it's not running on its normal internal clock. Long-term jet lag is associated with the same health risks as long-term sleep deprivation, including an increased risk of certain cancers, metabolic issues, heart disease, obesity, and diabetes.”
Natural sleep expert Dr. Catherine Darley added, “Based on sleep physiology, it makes sense that westward travel is easier, as it is easier to lengthen the circadian rhythm. Not only is mood worse, but people can feel an increase in anger and performance problems. It’s important to note that these effects can last for several days and to take that into account when planning. For those people who travel regularly, there are strategies that can decrease the disruption caused by jet lag.”
About Sleep Cycle
Sleep Cycle is the world’s most popular intelligent alarm clock app that analyzes users’ sleep, records findings and wakes them during their lightest sleep phase so they feel rested and refreshed. The app generates nightly sleep reports, tracks long-term sleep trends, and logs how daily activities impact sleep quality. With millions of users worldwide, Sleep Cycle has also become the world’s richest repository of data on global sleep habits. The Sleep Cycle Institute puts this data in the hands of five multidisciplinary health and wellness experts to provide individuals and public policy makers with deeper quantitative insights into the relationship between sleep and overall health and well-being.